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(No Model.) 4 Sheets-Sheet 1.

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TELEPHONE EXCHANGE APPARATUS. No. 420.183. Patented Jan. 28, 1890.

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No. 420,183. Patented Jan. 28, 1890.

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P. G. BEACH 81,- F. B. COOK. TELEPHONE EXGHANGE APPARATUS.

No. 420,183. Patented Jan. 28, 1890.

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TELEPHONE EXCHANGE APPARATU No. 420,183. Patentedian. 28, 1890.

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UNITED STATES PATENT OFFIC FRANKLIN G. BEACH, OF CHICAGO, ILLINOIS, ANDFRANK B. COOK, OF TOLEDO,

OHIO.

TELEPHONE-EXCHANGE APPARATUS.

SPECIFICATION forming part of Letters Patent No. 420,183, dated January28, 1890.

Application filed June 28,1889. Serial No. 315,904. (No model.)

T at whom it may concern:

Be it known that we, FRANKLIN G. BEACH,

' a citizen of the United States, residing at Chicago, in the county ofCook and State of Illinois, and FRANK B. COOK, a citizen of the UnitedStates, residing at Toledo, county of Lucas, and State of Ohio, haveinvented a certain new and useful Improvement in Telephone ExchangeApparatus, (Case 8,) of which the following is a full, clear, concise,and exact description, reference being had to the accompanying drawings,forming a part of this specification.

Our invention relates to apparatus for that class oftelephone-exchangein which the telephon e-lines are grouped upondifferent switchboards and trunk-lines provided for making connectionbetween any two of the switchboards as occasion may require.

The object of our invention is to simplify the circuits andto enable theoperators to signal between the different boards and to make thetransfer-connections with fewer motions-that is to say, with greaterfacility than heretofore, while at the same time obviatin g the troubleheretofore occasioned by one subscriber of a pair being left connectedupon one board after the other subscriber upon another board has beendisconnected, this trouble having frequently resulted from the operatorat the switch-board containing the switch of the called subscribereither not being provided with a clearing-out signal or failing todistinguish the clearing-out signals from signals caused by the firstoperator at tempting to call up the called subscriber. In brief,theQdelayin disconnecting the called subscriber has been usually theresult of failure of the operators to understand one another, whetherthe signals between the operators were given orally or electrically.Mistakes and consequent delays also have frequently resulted fromoperators misunderstanding the directions to make the connections. Byour invention all these delays are avoided, and the. operators areenabled to work silentlyand more rapidly than heretofore. 4

Our invention consists, first, in .a transfer switch or switches at eachboard connected with a'local circuit, including a signaling device atthe other boards and switching apparatus, whereby an operator at oneboard may signal the operator at any other of the boards and connect theline of the subscriber calling with the outfit of said other operatorand repeat the call to said other operator or permit said other operatorto receive the call as repeated by the calling subscriber; second, insucha construction of the transfer springjack switch as will cause thesignal in the local circuit from said transfer-switch to another boardto be operated when the disconnection has been made with the callingsubscribers line on pulling out the plug from the said transferspring-jack; third, in providing at each board a special switch andannunciator in a high-resistance ground branch connected with the localcircuit so arranged that any called subscriber who has been accidentallyleft connected may call up the operator by means of this specialannunciator, and the operator connecting with the special springjackswitch may findout what the trouble or want may be; fourth, in a specialconnecting and calling plug; fifth, in the special construction of thetransfer spring-jack switch, and, sixth, in the construction of thesignaling device or annunciator in the local circuit, whereby thesaidlocal circuit is maintained closed through the annunciator when theshutter is up and opened automatically to interrupt the circuit at saidannunciator when the shutter falls, thus preventing the possibility'ofthe annunciator being left in the closed circuit, even though theoperator should fail to insert the connecting-plug into thetransfer-switch far enough to open the local circuit at saidtransfer-switch.

Our invention is illustrated in the accompanying drawings, in which-Figure 1 is a diagram illustrative of two telephone-lines, eachextending through its switch and annunciator upontwo differentswitch-boards of the telephone-exchange, to-

gether with the connecting and signaling apparatus between the twoboards. Fig. 2 is a front elevation of three such switch-boards,- each'having a capacity of one hundred lines and each being provided with theusual individual and clearing-out annunciators, and in addition theretowith special signal devices or annunciators for receiving the signalsfrom operators at other boards. Fig. 3 is a detailed sectional view ofone of the transfer springjack switches. Fig. 4 is an enlargedsectionalView of the connecting and signaling plug. Fig. 5 is a front elevationof the circuit-opening drop. Fig. 6 is a side elevation thereof, partlyin section. Fig. 7 is a diagram of the trunk-lines and local circuitsfor three switchboards.

Like parts are indicated by similar letters of reference throughout thedifferent figures.

Telephone-line a is shown extending from ground at its station to thecentral office and r to its spring-jack switch a, and thence normallythrough its individual annunciator a to ground. Telephone-line b in likemanner is shown extending from ground at its subscribers station to thecentral office and to its spring-jack switch 19, and thence normallythrough its individual annunciator b to ground.

Referring now to Fig. 2, we will assume that the switch a and theannunciator a are those indicated upon board 3, and thatthe spring-jackswitch 1) and the individual annunciator b are those indicated by likeletters upon board 1 of Fig. 2. We will assume, too, that the subscriberof line a has called for the subscriber of line b, and that the twolines have been connected, as illustrated in Fig. 1. This connection ismade by the pair of cords and plugs 0 cl at board 3 and theconnecting-cord and connecting-plug e at board 1, the plug 0 beinginserted in spring-jack switch a, and the plug cl in the transferspring-jack switch fat board 3, and the connecting-plug e inserted inswitch I) at board 1, as shown more clearly in Fig. 1. Thistransfer-switch f,Iwill describe more in detail, as illustrated in Fig.3. It will be seen that the front portion f thereof is insulated fromthe frame f. The spring f normally rests in contact with said frontportion f The lever f normally rests upon the insulated contact f saidlever f being provided with a stud of insulating material, which, whensaid lever is lifted by the insertion of the plug and after it isseparated from its contact f takes the sprin g f from its normal contactwith the portion f of the switch. It will be understood that v theconnection f 6 is with the frame f of the switch. 'N ow on inserting aplug (as, for example, plug cZ, as shown in Fig. 1) in thetransfer-switchf the front portion f and the frame f will be connectedtogether through the shank of the plug, and the tip of the plug comingagainst the lever f said lever will be lifted from its contact withcontact-piece f and closed to the plug, and the plug being fullyinserted the lever f will be lifted far enough to bring the block ofinsulating material thereon against the spring f to lift and separatesaid spring f from the front portion f of the switch. Each board isprovided with, say, twice as many such transferswitches as there areother boards, so that several lines may be connected together betweenany two of the boads. A trunk or transfer line g extends from the frameor portion f of the transfer-switch at board 3 to the plug e at board 1,and it is this wire g that forms part of the talking-circuit-oftelephonelines a and b. The local circuit h is connected from thecontact f through the operators signal-drop t' and battery k, and thenceback to spring f of the transfer-jack. Now when the plug is inserted itcloses the local battery-circuit h momentarily as the plug first formsconnection between the front portion f of the switch and the framethereof; but this circuit is opened immediately thereafter by thefurther insertion of the plug, as before described. Now in case offailure of the transfer-switch to open the local circuit the batterywill not be left on short circuit, since the annunciator-drop in fallingoperates to automatically open the circuit. This signal-drop i will bemore readily understood by reference to Figs. 5 and 6. When the drop isup, the circuit h will be closed between contact 2" and spring 2' of theannunciator, spring 71 being pressed against said contact '5' by a stud2' upon the drop. This stud is preferably in the form of a screw, so asto be adjustable. The tension of the spring 75 is such that when theshutter is released and falls away the spring will by its own resiliencymove away from connection 2", so as to open the circuit at said contact.A highresistance branch Z is connected from this local circuit through aspring-jack switch Z and an annunciator Z? to ground, this branch havinga resistance of, say, one thousand ohms, so as not to short-circuit thebattery k. The signal-drop 'i may have a resistance ,of, say, threeohms, and the annunciator Z a resistance of, say, seventy-five ohms, andhence the current from battery is, passing through branch 1 at anytime,will not be suflicient to operate the annunciator Z in any event. U

Suppose the plug cl to be withdrawn from the transfer-switch f and thatfor some rea son the connection is left at switch I) with line b. Thesubscriber of line b by meansof his generator may send current over hisline to operate the annunciator Z and the operator at the boardcontaining said switch I)- in this instance. board Z-will see theshutter of annunciator Z fall, and this will be a signal of trouble, andshe will connect her telephone with the spring-jack switch Z, and thusplace herself in communication with the subscriber of line b.

In Fig. 1 we have shown a usual callingkey m, whereby current may besent to any line with which plug e is connected to call up thesubscriber thereon. We preferably, however, place this calling-keyuponthe connecting-plug e. The device thus formed we have termed aconnecting and calling plug,'this being illustrated in detail in Fig. 4,which we will now describe: This connecting and calling plug is providedwith the double-stranded cord n, one strand n being normally connectedwith the tip of the plug and the other strand n being connected with thecallinggenerator. terminal a against which the base of the metallicsleeve n of the plug is adapted to be closed. The screw or stud 77?,extending back within the rubber handle, has its head normally pressedagainst a contact-piece, with which the strand n is connected by thetension of a spring a The opening for this screw a in thesaidconnecting-plate is so large that when the sleeve n is pressed back, soas to separate the head of screw 01 from said plate, the connectionbetween said plate and said screw-head, and hence the connection betweenthe strand n and the sleeve n, will be broken, while a new contact willbe made between said sleeve 01, and the contact 07. The strands n n areshown slack, the strain of the cord coming entirely upon the clothforming the band or stop m The strain is thus entirely removed from thestrands. This plug, as shown in Fig. 4, may take the place of the plug 8and the callingkey m and generator-connection shown in Fig. 1. The plug,being inserted, will make proper connection with the telephone-line, andby simply pressing upon the handle, so as to coinpress spring 01 currentfrom the generator will be sent to line. Thus the act of inserting theplug may serve also to ring up the subscriber wanted. The tension ofspring a may be adjusted by means of the screw which is shown insertedin the top of the plug-that is, into the front end of the sleevecontaining said spring. The shank of the plug, being hollow, makes roomfor the spring a, which is fully protected thereby. The contact betweenstrand n and the stud n is covered by the rubber handle. In short, thereare no electric contacts of this plug exposed, so as to be either liableto injury or to be brought into contact with the hands of the operator.

Only one branch Z, containing a switch and annunciator P, will berequired at each board, since all the local circuits extending to agiven board may be connected with the same high-resistance branch;

\Ve have shown the usual. clearing-out annunciator 0 in Fig. 1. Ten suchclearing-out annunciators are shown provided on each board containingone hundred connections. These may be placed conveniently in ahorizontal row at the center of the board. The signal device 1' in thelocal circuits may be placed under the switches in a row, as shown. Thetransfer-switches fare most conveniently placed between the panelscontaining the individual switches. The special switch Z for each boardmay be conveniently placed, as shown, in the panel between the boards,and the annunciator Z may be placed immediately above the special switchZ.

The strand n is provided with a As shown in Fig. 7, the switch-board 3is provided with atransfer-switch f, a trunk-line circuit and a localcircuit 7t, extending to board 1. A similar trunk-line circuit extendsfrom transfer-switch p to board 2, a local circuit extending also toboard 2 being connected with this same transfer-switch p. In like mannerboard 2 has a transfer-switch, with which are connected a trunk-wire andlocal circuit extending to board 1, switchboard 2 being provided alsowith a transferswitch 4', with which are connected the trunkwire andlocal circuit extending to board 3. In like manner the transfer-switchess and t are connected, respectively, with boards 2 and 3, each by alocal circuit and a trunk-wire.

The high-resistance circuit Z, including the special switch andannunciator Z at board 1, is conncted not only with the local circuit hfrom board 3, but also with the local circuit from board 2. Thehigh-resistance circuit at each board may thus be common to all thelocal circuits extending to the particular switch-board thereof. r

We do not limit our invention to the details of construction sh own,since the arrange ment of the annunciators and switches upon theswitchboard and the particular form of the transfer-switches andsignal-drops and connecting and calling plugs may be varied according tocircumstances, as may be desired by different constructers.

Having thus described our invention, we claim as new and desire tosecure by Letter Patent- 1. The switch consisting of the front portionthereof insulated from the frame, a spring insulated from the frame andnormally resting in contact with the said front insulated portion, theswitch-lever and the contact-piece upon which said lever normally rests,said contact-piece being insulated from the frame, said lever carrying apiece of insulating material normally separated from the said insulatedspring, and a plug adapted to be inserted in said switch to first liftsaid lever from its contact and then force the piece of insulatingmaterial carried by said lever against said insulated spring to lift thesaid insulated spring from its normal contact with said front portion ofthe switch, whereby the plug forms a momentary connection between thefront portion of the switch and the frame thereof before the insulatedspring is lifted from said front portion, substantially as and for thepurpose specified.

2. The combination, with telephone-lines grouped upon differentswitch-boards at the central office of a telephone-exchange, of transferspring-jack switches, one or more on each board for each of the otherswitchboards, each transfer-switch being provided with a localsignal-circuit extending to one of the other boards and including asignal device or signal-drop, and each transfer-switch being providedalso with a trunk-line extending to the same board as the said local cirTIO cuit, and switching apparatus whereby the operator at one boardreceiving a call from one of her group of subscribers for a subscriberof another group may transfer the connection of said calling subscriberto the proper operator and signal said operator in so doingautomatically.

3. The combination, with two or more switch-boards, each provided withswitches for a difierent group of telephone-lines, of transfer-switches,one or more, each with a trunk-connection and local circuit extending toanother of the boards, the boards being thus provided with atrunk andlocal connection extending reciprocally from each board to all the otherboards, and plugs and cords at each board, whereby any line of one boardmay be connected with any line of another board and signals made betweenthe operators noiselessly and expeditiously, substantially as and forthe purpose specified.

4. A high-resistance ground branch, including a switch and annunciatorat one board, said high-resistance branch being connected with two ormore circuits leading to different transfer-switches each on anotherdifferent board, each of said transfer-switches being provided with atrunk-circuit extending to the board upon which are placed the switchand annunciator of said high-resistance local circuit, whereby asubscriber connected with either of said trunk-lines upon the boardcontaining the said annunciator and switch in the local circuit maybysending current over his line signal the operator, and the operator,seeing the signal, make connection with the said'subscribers line,substantially as and for the purpose specified.

5. The sleeve of the plug provided with the contact-piece n insertedthrough an opening in the plug, said connecting-piece 07. passingthrough a contact-plate having an opening larger than the portion ofsaid contact a passing through the same, the head of said contact-piecen being held against the said contact-plate by the tension of a spring,and the contact-piece a near the rear or base of said sleeve, wherebythe connections of said sleeve may be changed from the said contactplateto the contact a substantially as and for the purpose specified.

6. The combination, with the transferswitch f, constructed as described,of the trunk-circuit g, extending from the frame of said switch to aconnecting and calling plug at another board, the local circuit h,including a battery and signal-drop 2', said local circuit beingconnected with the spring f of said transfer-switch and the contact fthereof, whereby on inserting a plug in said transfer-switch the circuitof batteryk will be closed momentarily through signaldropi to operatethe same, while the tip of the plug thus inserted will be connected withthe lever of the switch and thence with the trunk-line, the

local circuit being open when the plug is fully inserted by the liftingof spring f from contact with the front portion f of the switch,substantially as and for the purpose specified.

7. The local circuit h, connected with a trans fer-switch, including abattery is and signaldrop 2', said signal-drop being provided with acircuit-opener included in said circuit It, said circuit-opener beingoperated to open the circuit of said battery is upon the falling of theshutter, substantially as and for the purpose specified.

8. The combination, with the shutter provided with the adjustable studor screw d of the spring '5 against which said screw is forced when theshutter is up to close said spring against a contact 2", said spring abeing adjusted to fall away from said contact 2" when the shutter isthrown down, thus removing the pressure from the contact-spring 2'thereby opening the electrical connection between said contact-spring '5and the contact a, substantially as and for the purpose specified.

9. Switch boards, each provided with switches for different groups oftelephonelines, and a local circuit extending reciprocally from eachboard to all the other boards, saidlocal circuits containing each abattery and a signal-drop, the signal-drop in each 10- cal circuit beingadapted to open the circuit thereof when thrown down, substantially asand for the purpose specified.

10. Two teleph one-lines, each provided with a spring-jack switch ondiiferent switchboards and connected. together between the two boards bya trunk-line connection, the circuit at one of said boards including aclearin g-out annunciator and atransfer-switch, said transfer-switchbeing connected with a local circuit having a signal-drop at the otherboard, whereby when the connecting-plug is withdrawn from saidtransfer-switch the said signal drop will be operated as a clearing-outsignal to the operator at the other board.

In witness whereof we hereunto subscribe our names this 18th day ofJune, A. D. 1889.

FRANKLIN G. BEACH. FRANK B. COOK. WVitnesses:

ELLA EDLER, O. G. HAWLEY.

